This invention relates to an overedge stitch, and more particularly to an improved apparatus for, and method of forming an overedge stitch for joining a plurality of material workpieces, and an improved stitch formed thereby.
In the formation of some overedge stitch seams it has generally been the custom to feed two pieces of work material that are to be joined through the sewing machine in superimposed relation with the edges of the material positioned in vertical alignment. Two fabric penetrating loops are formed by passing a pair of thread carrying needles, positioned in a side by side relationship, through the workpiece at points lying along a first line extending parallel with the edge of the workpiece. The loops formed by the second needle penetrate the workpiece at points lying along a second line spaced a greater distance from the edge than the line of penetration points of the first needle. An element of the machine interloops a lower or looper thread through the two needle loops whereby securing the first and second thread loops in the garment. This third loop of thread is carried to the edge of the workpiece by said element and pierced by a subsequent thread loop, or upper looper thread. The upper looper thread is then passed over the upper surface of the top ply and pierced by a subsequent fabric penetrating loop. The completed seam finds the two plies of fabric in overlying relationship with the seam extending along a common edge of the two plies. The type of stitch produced by such a machine and described hereinabove is generally referred to as a Federal Stitch Type 512. However, this type of stitch has certain disadvantages when used on garments employing inferior grades of thread. That is, the tightness of the stitch, and more particularly the interlooping of the first and second needle thread loops with the third or looper thread causes pucker of the garment which in many instances may produce an undesirable and unacceptable garment. In addition to this, and as will become apparent hereinafter, there is only a single overedge thread protecting the edge of the garment whereas with the present invention a plurality of threads are employed to secure or cover the edge of the garment whereby resulting in a probability of a lesser chance for the edge of the fabric to ravel.